• Prior interaction with an author’s posts: If you like every post by a page that Facebook shows you, it will show you more from that page.
• Other people’s reactions to a specific post: If others on Facebook are shown a post and ignores it, or complains, it’s less likely to show up on your news feed.
• Your interaction with posts of the same type in the past: If you always Like photos, there’s a better chance you’ll see a photo posted by a page.
• If a specific post has received complaints by other users who have seen it, or the page who posted it has received lots of complaints in the past [aka “Negative Feedback” metric], you’ll be less likely to see that post. This factor became a lot more prevalent with the EdgeRank update in September 2012.

Source: EdgeRank Checker, Nov. 2012